If you’re serious about building your cycling fitness, you’ll almost certainly know that interval training is one of the very best tools to achieve your goals.

The reason is simple; interval training allows you to get bigger fitness gains, faster than simply pedalling along endlessly at a steady intensity.

For those new to intervals, interval training is basically a method of training that intersperses intervals or bursts of high-intensity cycling, with short periods of rest. However, because the permutations are endless (number of intervals, interval length, interval intensity, length of rest period), one question that continually crops up is: what type of interval workout should I be doing?

There’s no hard and fast answer, but new research by Norwegian scientists suggests that too long an interval length could be less effective when it comes to producing fitness gains.

The science
In the study, scientists looked at the effects of three different interval durations in 13 well-trained cyclists. To do this, they first measured the minimum power output that each cyclist had to produce in order to reach their peak oxygen uptake – basically the cycling intensity where the oxygen transport system is maxed out.

Because this is a very high intensity, this power output can’t be sustained for long periods of time but it can be a very effective intensity for gains in aerobic fitness. In the first part of this study, the cyclists had to pedal to exhaustion at this minimum power output; the time each cyclist lasted before exhaustion was reached (time to exhaustion) was recorded.

In the second part of the study, the cyclists performed three interval-training protocols to exhaustion:
1. Work intervals at the above minimum power output lasting 80 per cent of recorded time to exhaustion, with a recovery duration of half the interval duration;

2. Work intervals at the above minimum power output lasting 50 per cent of recorded time to exhaustion, with a recovery duration of half the interval duration;

3. Work intervals at the above minimum power output lasting just 30 seconds, with a recovery duration of 15 seconds.

In particular, the researchers wanted to find out which interval protocol resulted in the most total work being done at this power output before tiredness set in.

In a nutshell
The main finding was that although the 30-second intervals were much shorter than those lasting 80 per cent and 50 per cent of recorded time to exhaustion, the cyclists were able to accumulate much more total time working at near to their peak oxygen uptake, and were able to sustain their interval session for significantly longer periods than when they did fewer, longer intervals – those lasting 50 per cent or 80 per cent of time to exhaustion in stage one.

So what?
The fact that a 30 seconds work/15 seconds rest interval protocol enabled the cyclists to accumulate much more total time at high intensity is important for two reasons; firstly, it suggests that for a given time accumulated in the high-intensity zone, the 30-second intervals are much easier on the body and result in less fatigue.

The second implication for fitter cyclists is that if you’re planning some high-intensity intervals to develop your aerobic power, 30-second intervals at the power required to reach your maximum oxygen uptake (with 15-second recovery periods) is a good place 
to start.

This article was first published in the October 17 issue of Cycling Weekly. Read Cycling Weekly magazine on the day of release where ever you are in the world International digital edition, UK digital edition. And if you like us, rate us!